The present invention relates to a position finder for vehicles having a satellite receiver connected to an antenna for receiving and evaluating transmitted signals sent by a plurality of satellites, additional sensors for detecting the movement of the vehicle, and a coupler computer for joint evaluation of the transmitted signals sent by the satellites and of the sensor signals so that instantaneous positional data can be generated.
Position finders for vehicles maybe used, in particular, as part of navigation systems for land-, air- and water-based vehicles. In navigation systems for motor vehicles, an antenna for receiving transmitted signals sent by the satellites is arranged on the vehicle""s exterior, and the signals received are sent to the respective receiver via shielded lines. As a general rule, the receiver is part of a navigation device in which the extensive data for navigation, e.g., maps and street information, can be queried. The instantaneous positional data allow accurate navigation information to be output based on the queriable navigation data. As a general rule, navigation information is output in the form of spoken information, as well as in the form of symbols and driving commands reproduced on a separate display.
By using additional sensors, the current position can be determined with a greater precision than is feasible via satellite navigation for civil applications. The additional sensors allow the vehicle""s position within a given limited region to be determined with greater precision, if initial positioning information is provided. However, if the vehicle travels a long distance, the unavoidable errors in the output signals of the additional sensors become cumulative. Satellite navigation, which in civil applications allows positional accuracy of about 100 meters, can then be used within a given extended region to correct the position determined by the additional sensors.
The motor vehicle""s wheel sensors, which are used for automatic brake control (ABS), may be used as the additional sensors.
Thus when a navigation system is used the output signals of the wheel sensors and any other sensors must be evaluated and used to define a position. The positional data generated in this way is sent to the coupler computer, along with the positional data generated based on the signals sent by the satellites, and evaluated in a complex manner so that the instantaneous position can be determined.
It is desirable to improve the precision of the positional data determined based on the satellite signals, and for this purpose differential correction data in the VHF range are transmitted and, with the help of the appropriate antenna, can be received and evaluated using an appropriate receiver.
Thus when installing a related-art navigation system, one must provide the necessary antenna/antennae, implement the accompanying receiver in a device inside the vehicle, and gather sensor signals from the vehicle system, for example, from the wheel sensors of an automatic brake control (ABS) system. This involves considerable cost, so navigation systems in vehicles are very expensive at the moment.
Based on the object, according to the present invention a position finder for vehicles of the type described above is characterized in that the additional sensors are exclusively sensors that are independent of the vehicle system, and the satellite receiver, along with its antenna, additional sensors and coupler computer, are arranged in a separate box having a power supply terminal and an interface via which positional data can be transmitted.
The position finder according to the present invention is based on a new concept in which the complete position finder for determining the instantaneous positional data is housed in a separate housing and is independent of the vehicle system in terms of positioning functionality. As a result, the position finder according to the present invention can be installed very easily, in particular, as a retrofit product. Aside from the power supply, all that is required is an interface via which the positional data can be sent from the position finder to a navigation device inside the vehicle, and via which, if necessary, data can be sent to the position finder, for example, to initialize it.
The position finder according to the present invention allow one to implement an inexpensive design in which complete positioning functionality is carried out by the position finder according to the present invention, and the instantaneous positional data that is generated is sent to a computer inside the vehicle which is supplied with navigation information and generates navigation recommendations based on the current positional data. According to the present invention, the computer inside the vehicle can be a standard computer, e.g., a laptop in a special holder that does not have to be permanently installed. Thus one can ensure that the amount of installation required within the vehicle is kept to a minimum, while the space required is also kept to a minimum.
A further advantage of the present invention is that the signals received by the antenna/antennae can be processed immediately without the need for long wires. In addition, because the satellite receiver and the additional sensors are arranged in the same housing, one can use the same processor to evaluate the given sets of raw data, so various simplifications are possible. As a result, it is unnecessary to first calculate the positional data based on satellite positioning and based on the additional sensors separately, and then couple the two sets of data. Instead, coupling can be carried out before the raw data are evaluated and turned into positional data.
In a particular advantageous embodiment of the present invention, the housing is designed so that it can be mounted on the vehicle""s exterior, in particular, on the roof.
A complete devicexe2x80x94including antennaxe2x80x94for evaluating differential data for satellite positioning can easily be integrated into the position finder according to the present invention.